1. Field of the Invention
The present invention relates to a method of disposing of gas generators from unused air-bags which are scrapped with automobiles in an environmentally acceptable manner.
2. Description of the Prior Art
Air bag units for automobiles are widely used throughout the world. They are installed to protect passengers during a crash. Generally, an air bag unit comprises an air bag and a gas generator unit. Upon impact the gas generator unit is actuated and instantaneously releases gas to rapidly expand the air bag. The inflated air bag forms a cushion between the passenger and, for example, the steering wheel to prevent the passenger from impacting against the steering wheel as he or she is flung forward when the automobile rapidly decelerates.
The gas generator has a metallic housing. A gas generating agent is disposed in the housing along with an ignition means for igniting the agent. The ignition means is designed to be actuated by mechanical shock. Actuation of the gas generating agent causes rapid combustion which generates gas to instantaneously inflate the air bag.
Typically the housing for a gas generator is made of, for air bag.
Typically the housing for a gas generator is made of, for example, aluminum alloy and stainless steel. The gas generant typically has as primary components, for example NaN.sub.3 (sodium azide) and CuO (copper monoxide). In addition, the gas generator can include a filter, a coolant, a sealant and a cushion, all of which contain organic compounds having carbon (C) and nitrogen (N).
During the combustion process of the gas generant, many reactions can occur between the foregoing components. For example: EQU 2NaN.sub.3 +CuO.fwdarw.Na.sub.2 O+Cu+3N.sub.2
When the gas generator is activated the nitrogen gas generated explodes into the air bag leaving behind in the gas generator Na.sub.2 O (sodium oxide) contaminant. The Na.sub.2 O can subsequently react with moisture and carbon dioxide in air to form an alkali, e.g. sodium hydroxide and sodium carbonate: EQU Na.sub.2 O+H.sub.2 O .fwdarw.2NaOH (Sodium hydroxide)
and EQU Na.sub.2 O+CO.sub.2 .fwdarw. NA.sub.2 CO.sub.3 (Sodium carbonate)
The sodium hydroxide and sodium carbonate contaminants are alkaline compounds and if not controlled can pollute the environment.
Additionally, upon actuation of the gas generator the carbon-nitrogen containing organic compounds used in the generator thermally decompose to form cyano compounds (--CN). These cyano contaminants are toxic as well as also being environmental pollutants.
When automobiles are scrapped, they are usually compressed. If an automobile is compressed with an unused air bag unit therein, there is the risk that the air bag unit will explode. In order to avoid this risk, the scrapping process is carried out only after actuation of the gas generator. Typically, automobile manufacturers have the following disposal instructions:
1. For electric system gas generators--a prescribed current is applied to the unactuated gas generator by wires leading from a battery. This actuates the gas generator. This may be accomplished either with the device in the car or may be accomplished by removing, for example, the steering wheel from the car. PA1 2. For mechanical system gas generators--The gas generator is removed from the car, placed within scrapped or used tires and then mechanically actuated. PA1 a) heating the gas generator, preferably between about 150.degree. C. and 450.degree. C., to actuate the generator to produce combustion gases and an actuated generator having water soluble contaminants, typically alkaline and/or heavy metal ions, thereon; PA1 b) washing the actuated generator with a water composition to remove the contaminants from the actuated generator to produce a washed generator and a contaminated water composition; PA1 c) dividing the washed generator to produce divided generator parts; PA1 d) chemically treating the contaminated water composition to produce a purified water composition, preferably by neutralizing the contaminated water with an acid to a pH between about 6 and 8; and PA1 e) classifying the divided generator parts into classified generator parts by, for example, magnetic classification, gravitational classification, manual classification or combinations thereof.
Potential problems exist even when the car is compressed after actuation of the gas generator. As indicated previously, the actuation of the gas generator causes Na.sub.2 and --CN contaminants to remain in the gas generator. Therefore, when the automobile is compressed there is a risk that this will cause the Na.sub.2 O and --CN compounds to scatter. This can lead to a violent reaction with water and/or the polluting the environment with toxic and environmentally undesirable --CN compounds.
If, on the other hand, the gas generators are removed from the automobiles and scrapped separately from the automobiles, the toxic and environmental contaminants, i.e. Na.sub.2 O and --CN compounds can be similarly scattered when, for example, the gas generator is cut into smaller pieces. Such scattering of the contaminants can cause safety, health and environmental problems.